Engine starter gearing



oct. 19, 1943. B. w. JONES 2,332,086

ENGINE STARTER GEARING Filed Dec. 6, 1941 2 Sheets-Sheet 1 INVENTOR. BY 5M/:r fw. ign/es A 7" TOR/VE Y Oct. 19, 1943. B, w. JONES ENGINE STARTER GERING Filed Deo. 6. 1941 2 Sheets-Sheet 2 INV ENT OR.

A TTORNEV Patented Oct. 19, 1943 UNITED STATES PATENT OFFICEN ENGINE STARTER GEARIN G Burr W. Jones, Elmira Heights, N. Y., assignor to Bendix Aviation Corporation, South Bend, Ind.,

a corporation of Delaware Applica-oon December s, 1941, serial No. 421,982

(c1. 29o-ss) 6 Claims.

The present invention relates to engine starter gearing and more particularly to a magnetic detent for ensuring traversal of a starter drive pinion by means of a threaded connection.

In heavy duty types of starter drives, particularly when the drive pinion is actuated from the starting motor through reduction gearing, the traversal of the drive pinion into mesh with the engine gear is sometimes sluggish in lcold weather, especially in the presence of ice or congealed oil. Various forms of detents have been proposed to resist rotation of the pinion to ensure its traversal under such circumstances. One such detent which is arranged to momentarily engage a starter pinion upon actuation of the starting mechanism is disclosed in the application of Elkin, Serial Number 392,724, nled VMay 9, 1941.y

It-ls an object of the present invention to provide a starter drive incorporating a novel form of detent forensuring'traversal of the drive pinion.

It is another object to provide such a device in which the detent is arranged to move into engagement with the drive pinion prior to energilation ofthe ystarting motor, and is held in such engagement only for. suiiicient time to ensure initial engagement of the pinion with the. engine gear.

Another object is to provide such a device in which the detent is yieldingly pressed against the pinion so that if it strikes the top of a gear tooth, it will be snapped into a tooth space as soon as the pinion starts to turn. Y

Another object is to provide such a device incorporating apneumatic cushion for the detent.

Further objects and advantages will be apparent from the following description, taken in connection with the accompanying drawing., in which:

' Fig. 1 is a semi-diagrammatic illustration of a starting system showing a double reduction starter drive insideelevation, and showing a detent. structure consisting a preferred embodiment of the invention, the parts being partly broken away and in section;

Fig. 2 is a view similar to Fig. 1 showing the parts in the positions assumed during traversal of the pinion into mesh with the engine gear; and

Fig. 3 is a similar view showing the parts in the positions assumed during the cranking operation.

In Fig. 1l of the drawings there is illustrated a starting system comprising a battery I grounded at 2 and connected by a lead 3 to a starting switch contact 4. A second starting switch contact 5 is connected by a lead 6 to a starting motor SM 55 which is grounded by a lead I to complete the starting circuit.

The extended armature shaft of the starting motor is illustrated at 8, journalled in a bearing 9 of the motor housing and having a pinion I2 keyed thereon in any suitable way. A low-speed shaft I3 is journalled at I4 in the motor housing and is provided with an out-board bearing I5 in an extension I6 of the motor housing. Shaft I3 has a gear keyed thereon as indicated at I8 which gear is arranged to mesh with the pinion I2 to transmit rotation from the starting motor to the shaft.

Shaft I 3'is provided with a threaded portion I9 on which an interiorly threaded starting pinion 2| is mounted for longitudinal movement into and out of engagement with a gear V2i. of an engine to be started. Anti-drift means including a spring 23 and thrust collar 24 normally maintain the starting pinion in idle position as illustrated in Fig. 1, the thrust collar 24 being arranged to abut against a shoulder 25 on the low-speed shaft and thereby deiine the cranking position of the pinion as shown in Fig. 3.

According to the present invention a detent is provided for momentarily engaging the starting pinion 2| prior to the rotation of the shaft I3 by the starting motor in order to resist initial rotation of the pinion 2| and thereby assure its traversal into mesh with the engine gear 22. As here shown a cylindrical detent member 2S is slidably mounted in a bearing member 21 which is threaded in the housing extension I6 in position to permit the tapered end 28 of the detent to engage between the teeth of the pinion 2| when the detent is in projected position. The detent is normally maintained retracted by means of a spring 29 engaging a shoulder 3| in the bearing member 2T and a terminal flange 32 on the detent. The idle position of the detent is defined by a sleeve 33 pressed into the bearing member 21 surrounding the detent and having a shoulder 34 engaging the upper end of the detent.

Means for actuating the detent is provided in the form of a plunger 35 slidably mounted within the detent and having a stem 36 on which an armature 31 is mounted seated against a shoulder 38, the armature being normally maintained in its upper position as shown in Fig. 1 by means of a spring 39.

Electro-magnetic means for actuating the armature to move the plunger downward is provided in the form of a solenoid 4| connected at one end through a lead 42 to the starting switch contact 4, and by a lead 43 through a push button 44 to the ground at 45 to complete the control circuit for the detent. A bridging contact member 46 is slidably mounted on the stem 36 of the plunger, spaced from the armature 31 by a sleeve 41 and yieldably pressed against the sleeve by a spring 48 connected to the stem through a thrust nut 49. The length of the sleeve il is so chosen that the Contact 46 is caused to bridge the starting switch contacts 4 and 5 after sufficient longitudinal movement of the plunger to cause engagement of the detent 26 with the pinion 2 I,

Means are provided for elastically .connecting the detent to the plunger during the downward actuation of the plunger so as to press the plunger into engagement with the starting pinion, and to relieve such elastic pressure after a predetermined time when the plunger has completed its downward stroke. As shown, this is accomplished by forming the plunger 35 with two spaced cylindrical portions 5| and 52 loosely iitting the interior of the detent 26 so as to act as dashpot pistons therein, and by providing a vent for the air trapped below the piston portion 5l comprising a canal 53 through the piston 5I, a port 54 through the side of the detent 26 and an opening 55 in the bottom of bearing member 2l.

Port 54 is so located with respect to the piston' 5I that initial downward movement of the piston closes the port, thereby trapping air below the piston to form an elastic cushion for the transmission of movement from the plunger 35 to the detent 26. When the plunger has completed its movement as shown in Fig. 2, however, the port is uncovered, thus venting the cylinder in the detent and permitting the detent to be raised out of operative position by the spring 29 as shown in Fig. 3. It will be understood that the bearing member 21, plunger 35 and detent 26 will preferably be formed of non-magnetic material, but the sleeve 33 may preferably be formed of magnetic material such as soft iron in order to decrease the reluctance of the magnetic circuit of solenoid 4| and increase the holding power of the solenoid on the armature 3l.

In operation, starting with the parts in position as illustrated in Fig. 1, closure of the push button 44 by the operator completes the control circuit for the solenoid 4I which is thereby energized by the battery I and attracts the armature 3l, moving the plunger 35 downward. This movement is transmitted to the detent 26 through the elastic cushion of the air trapped in the detent below the piston 5I whereby the detent is moved into engagement with the drive pinion 2I to resist its rotation. Further movement of the plunger 35 causes the bridging Contact 46 to be pressed into engagement with the starting switch contacts 4, 5 by the spring 48 whereby the starting motor SM is energized and rotation transmitted through pinion I2 and gear I1 to the shaft I3 whereby the starting pinion 2| is threaded along said shaft into engagement with the engine gear 22.

The plunger 35 continues to move downward under the impulsion of the solenoid 4I after the starting switch has closed and the detent 26 has bottomed on the starting pinion 2l due to the loose t of the dashpot pistons 5I and 52 in the detent. When the piston 5I thus uncovers the port 54, the dashpot is vented and the detent is immediately returned to idle position by its spring 29. lt will be understood that this entire operation takes place very quickly, since the traversal of the starting pinion into initial mesh with the engine gear requires only a small amount of rotation of the screw shaft I3 by the starting motor.

When the engine starts, the operation releases the push button 44, thus de-energizing the solenoid 4I and permitting the parts to return to their idle positions.

Although but one embodiment of the invention has been shown and described in detail, it will be understood that other embodiments are possible and that changes may be made in the design and arrangement of the parts without departing from the spirit of the invention as deiined in the claims appended hereto.

What is claimed is:

1. In an engine starter including a pinion and threaded means for traversing the pinion into operative position, a detent for resisting rotation of the pinion to ensure its traversal, and electro-magnetic means for projecting the detent into engagement with the pinion, said detent comprising a hollow cylindrical member and said electromagnetic means comprising a plunger telescoped therein, and yielding means normally holding the cylindrical member and plunger in extended relation.

2. The structure set forth in claim 1 including further, pneumatic means for resisting the telescoping of the parts of the detent.

3. The structure set forth in claim 1 including further, pneumatic means for resisting the telescoping of the parts of the detail and means for venting the pneumatic means after a predetermined telescoping movement of said parts.

4. In an engine starter, a motor, a pinion,

means including a threaded connection actuated by the motor for moving the pinion into engagement with an engine gear, a detent `for resisting rotation of the pinion to ensure its traversal including a plunger and a cylinder in telescopic relation therewith, and yielding means normally holding said parts in extended relation, electro-magnetic means for actuating the plunger to project the cylinder into engagement with the pinion, switch means actuated by said electro-magnetic means for causing energize.- tion of the starting motor, and means for withdrawing the cylinder from the pinion after a predetermined time.

5. In an engine starter a motor, a pinion, means including a threaded connection actuated by the motor for moving the pinion into engagement with an engine gear, a detent for resisting rotation of the pinion to ensure its traversal including a plunger and a cylinder in telescoping relation therewith, -yielding means normally holding said parts in extended relation, pneumatic means for resisting telescopic movement of said parts, electro-magnetic means for actuating the plunger to project the cylinder into engagement with the pinion, switch means actuated by said electro-magnetic means for causing energization of the starting motor, and means for venting the pneumatic means and withdrawing the cylinder from the pinion after a predetermined traversal of the plunger beyond switch-closing position. 1

6. In an engine starter a motor, a pinion, means including a threaded connection actuated by the motor for moving the pinion into engagement with an engine gear, a detent for resisting rotation of the pinion to ensure its traversal, said detent including a slidably mounted plunger, and a cylinder slidably tting the plunger to form a dashpot therewith, yielding means normally holding the plunger and cylinder in extended relation with the cylinder disengaged from the pinion, electro-magnetic means for actuating the plunger to project the cylinder into engagement with the pinion, a. starting switch for the motor arranged to be closed by the plunger after the cylinder is moved into engagement with the pinion, and means for venting the dashpot to permit the cy1inder to be returned to idle position after a predetermined movement of the plunger beyond the switch-closing position.

BURR W. JONES. 

